Topological dimension of vertex meshes is wrong

[jorgensd]

Summarize the issue

A mesh consisting of vertices gets topological dimension 1, instead of zero.
Most likely introduced in: #3512
Does work on 0.9.0

How to reproduce the bug

Run the following code

Minimal Example (Python)

from mpi4py import MPI
import dolfinx
import numpy as np
mesh = dolfinx.mesh.create_unit_cube(MPI.COMM_WORLD, 3,4,7, cell_type=dolfinx.cpp.mesh.CellType.tetrahedron,
                                         ghost_mode=dolfinx.cpp.mesh.GhostMode.shared_facet)
edim = 0
mesh.topology.create_entities(edim)
emap = mesh.topology.index_map(edim)
num_entities_on_proc = emap.size_local + emap.num_ghosts
subset_cells_local = np.arange(num_entities_on_proc, dtype=np.int32)
submesh, entity_to_parent, vertex_to_parent, _ = dolfinx.mesh.create_submesh(mesh, edim, subset_cells_local)
assert submesh.topology.dim == edim, f"{submesh.topology.dim} != {edim}"

Output (Python)

Traceback (most recent call last):
  File "/root/shared/dolfinx/python/test/unit/mesh/mwe.py", line 12, in <module>
    assert submesh.topology.dim == edim, f"{submesh.topology.dim} != {edim}"
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: 1 != 0
root@dokken-XPS-9320:~/share

Version

main branch

DOLFINx git commit

a547191

Installation

No response

Additional information

No response